The antibiotic rifamycin S is a physiologically active derivative of the microbial fermentation product rifamycin B. Traditional methods of producing rifamycin S from rifamycin B require a complex, multi-step process. For example, rifamycin B can be oxidized by hydrogen peroxide or ammonium persulfate to the intermediate compound rifamycin O, subsequent acid hydrolysis of which yields rifamycin S. See T. Korzybski et al., Antibiotics, Volume I, pp. 250-267 (Pergamon Press, 1967).
Conventional solvent extraction techniques used for the recovery of these rifamycin derivatives require the use of large volumes of solvent and/or repetitive extractions. In addition, by-products are often extracted and concentration steps are usually required. More efficient recovery of the rifamycin derivatives at various stages in the fermentation process could lead to improved yields and/or process simplification.
Ion exchange resins have been used in the purification and recovery of certain antibiotics and other biologically active materials. For example, streptomycin has been adsorbed from a liquid culture by weakly acidic ion exchangers. J. Buchi, J. Pharm. Pharmacol., 8, 379 (1956). Strong base resins have proven useful for work with phenolic compounds, for example, the recovery of the antibiotic novobiocin from a fermentation broth, U.S. Pat. No. 3,000,796 (1961); and for concentration of tocopherol, U.S. Pat. No. 3,122,565 (1964).
However, rifamycin derivatives are more difficult to work with than other biologically active materials because rifamycin derivatives are readily decomposed under basic conditions as well as under anhydrous acidic conditions. Therefore, the conditions used and the methods employed for the recovery of the rifamycin derivatives are important.